1664242381 has 2 divisors, whose sum is σ = 1664242382. Its totient is φ = 1664242380.

The previous prime is 1664242339. The next prime is 1664242397. The reversal of 1664242381 is 1832424661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1648766025 + 15476356 = 40605^2 + 3934^2 .

It is a cyclic number.

It is not a de Polignac number, because 1664242381 - 2⁹ = 1664241869 is a prime.

It is a super-2 number, since 2×1664242381² = 5539405405433098322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1664242381.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664242331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832121190 + 832121191.

It is an arithmetic number, because the mean of its divisors is an integer number (832121191).

Almost surely, 2^1664242381 is an apocalyptic number.

It is an amenable number.

1664242381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664242381 is an equidigital number, since it uses as much as digits as its factorization.

1664242381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 55296, while the sum is 37.

The square root of 1664242381 is about 40795.1269271221. The cubic root of 1664242381 is about 1185.0559608484.

The spelling of 1664242381 in words is "one billion, six hundred sixty-four million, two hundred forty-two thousand, three hundred eighty-one".